Effects of Heat Treatment on Microstructure and Wear Behavior of Modified Aluminum Bronze Coatings Fabricated by Laser Cladding

In this paper, the effects of heat treatment on microstructure and properties of modified aluminum bronze alloy coatings were studied. In order to clear out this question, Cu-7Al-3Fe-3Ni alloy was fabricated on 316 stainless steel by laser cladding. And a subsequent heat treatment which tempered four samples at 500, 600, 700 and 800 °C for 1 h, respectively. The deposited coatings mainly contained α-Cu, β’(AlCu3), κ((Fe,Ni)Al) and Cr-Fe phases according to the analysis of XRD and SEM images. After tempered at 500 °C for 1 h, content of κ phase in the coating increased, and there was residual β’ phase. These two hard phases made the coating tempered at 500 °C had the lowest coefficient of friction and wear rate. Then with the increase of tempering temperature, both α-Cu and other phases became coarsen. The results of microhardness showed that the microhardness was significantly improved after heat treatment. Especially, the samples which tempered at 500 °C for 1h showed a better performance of microhardness. With the tempered temperatures increased, the microhardness at interface decreased from 517 HV (500 °C) to 312 HV (800 °C). The EBSD results showed that there was no obvious preferred orientation for grains of deposited and tempered samples, and the Schmidt factor and KAM were both significantly decreased after heat treatment.